Replicant2 does not have any module class suffixes accompanying it. If you wish to engage in adding your own module hilites, then the following tutorial will help you tremendously, Module Styling Tutorial.
If you decided to add your own suffixes to the template code, you will need to know how to apply the suffix to the module. For this, you need to login into the Joomla administrator and located the Module Manager. Find your module in the list and find the field termed as Module Class Suffix, insert your suffix here.